The (001) crystal surface of RbTiOPO4 (RTP) were bombarded by Ar+ ion during different times (2–20 min) and the resulting chemical modification on surface has been studied by X-ray photoelectron spectroscopy (XPS) and first-principles calculations. Ion bombardment can lead to great structural modification on the surface of RTP crystal. Reduction of Ti4+ ions to the lower valence state (Ti3+) and formation of oxygen vacancies occur with Ar+ ion irradiation. With the increase of irradiation time, proportion of reduced Ti3+ ions and number of oxygen vacancies increase accordingly. Fraction of oxygen in P-O-Ti bonds decreases with increasing oxygen vacancies after bombardment for 5–20 min. We think that oxygen vacancies come from breaking of P-O-Ti bonds. The results were also confirmed theoretically by first-principles calculations. Existence of oxygen vacancies is also confirmed by absorption spectra. Formation of Ti3+ state can be ascribed to the loss of surrounding oxygen caused by Ar+ ion irradiation. This work helps us to better understand the ion-beam interaction with RTP surfaces.

Ternary alloys of composition close to Cr2AlC have been deposited by ion beam sputtering onto unheated and heated to 380 degrees C Si substrates. As-deposited films are amorphous. Annealing of the film in vacuum at 700 degrees C leads to crystallisation with 39.2 nm crystallites. Crystallisation also can be achieved by annealing in air but there is also partial oxidation of the film surface to the depth of approximately 120 nm, which represents an oxide layer less than 5% of the total film thickness. There is an increase of lattice size along the c-axis during crystallisation in air, which indicates a small incorporation of oxygen. Film structure and crystallisation have also been analysed by Raman spectroscopy. Changes in Raman spectra in Cr2AlC have been correlated with the film crystallisation and it was observed that MAX-phase related peaks become clearly defined for the crystallised film. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.

A brief history of the journal Vacuum is given covering its launch in 1951 as volume 1 of an in-house journal of Edwards High Vacuum Ltd to its present 100th volume, now as an Elsevier journal.

Titanium Silicon Carbide films were deposited from three separate magnetrons with elemental targets onto Si wafer substrates. The substrate was moved in a circular motion such that the substrate faces each magnetron in turn and only one atomic species (Ti, Si or C) is deposited at a time. This allows layer-bylayer film deposition. Material average composition was determined to Ti0.47Si0.14C0.39 by energy-dispersive X-ray spectroscopy. High-resolution transmission electron microscopy and Raman spectroscopy were used to gain insights into thin film atomic structure arrangements. Using this new deposition technique formation of Ti3SiC2 MAX phase was obtained at a deposition temperature of 650 degrees C, while at lower temperatures only silicides and carbides are formed. Significant sharpening of Raman E-2g and A(g) peaks associated with Ti3SiC2 formation was observed. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.

A method for simulating the thickness distribution of cubic boron nitride (cBN) films deposited on a curved substrate using ion-beam-assisted vapor deposition (IBAD) is established and discussed. The deposition conditions are (i) boron arriving rate is 3.2 angstrom/s, (ii) ion current density is in the range 600-1600 mu A/cm(2), and (iii) gas composition fed into the ion source is 36% N-2 + Ar. It was found that, due to simultaneous deposition and sputtering, the boron resputtering yield (which depends on the ion incident angle during cBN deposition) estimated from experimental data was higher than that of the boron sputtering yield of the BN films with a density of 3.482 g/cm(3) calculated by the TRIM code. Using the above empirical boron resputtering yield, it is estimated that in the case of static coating, cBN films would not be formed when the incident angle is more than 40 degrees. However, with continuous waving, the distribution of film thickness improves and the results are consistent with the experimental results. This estimation also agrees with the experimental results of discrete waving deposition within an allowable margin of error (C) 2012 Published by Elsevier B. V. Selection and/or peer review under responsibility of Chinese Vacuum Society (CVS).

Influence of ion/atom arrival ratio and ion energy on residual stress of BN films were investigated using the dual ion beam sputtering (DIBS) method. The dual ion beam deposition system comprises two Kaufman type ion sources. The sputtering ion source, which is directed to a target, can provide an ion beam at a selected energy in the range of 1000-1500 eV and a current density of 0.5-1.5 mA/cm^2. The assisting ion source having two grids provides an ion beam at a selected energy in a range of 100-800 eV and a current density of 〜100 μA/cm^2. The internal stress was estimated by a bending method. A coated silicon substrate has curvature caused by the deposition. The curvature was measured by a surface profilometer with a stylus tracking force of 10 mgf. RBS analysis was conducted with ^4_2He^+ ions as the projectile which were extracted from a 2 MeV Van de Graaff accelerator, with a total scattering angle of 168° and a beam incident angle to the substrate normal or 60 deg, so that the composition of the prepared BN thin films including Ar content was measured. With regard to the influence of the ion/B arrival ratio on the stress of BN films, it was found that (a) the Ar content increased to 8 at.% with increasing ion/B arrival ratio, whereas (b) the stress of the BN films increased to around 3.8 MPa at an ion/B arrival ratio of 0.75,then decreased with the increase of the ion/B arrival ratio. It has been suggested that the increase of stress at lower ion/B arrival ratios could be caused by lattice strain produced by the change of composition and crystal structure from boron to BN, and after the composition and crystal structure reach BN, excess energy may be used to create Ar and N_2 bubbles, resulting in stress relief. From a series of experiments varying the ion energy from 300 to 850 eV keeping others constant, it was found that the Ar content and stress of the BN films decreased with increasing ion energy. It has been suggested that the decrease is due to the annealing effect by supplying higher energy.

TiFeN and TiFeMoN films were deposited on silicon wafers by ion-beam-assisted deposition. Their mechanical properties were measured by nanoindentation (quasi-static) and nano-impact (dynamic) techniques. Nano-impact testing enabled assessment of their toughness and resistance to fatigue fracture under repetitive loading. At low impact forces, films with a higher resistance to plastic deformation ( H 3 / E 2 ) were much more resistant to the formation of cracks throughout the test. At higher impact forces, these films initially show impact resistance but with continued impacts they are unable to protect the Si substrate, performing as poorly as films with lower H 3 / E 2 and suffer delamination from the Si substrate over a large area.

Silicon carbo-nitride films with Boron were deposited onto Silicon, glass and SS304 Stainless Steel substrates using the ion beam assisted deposition (IBAD) method. The coating composition, rate of ion-assistance and substrate temperature were varied. Films were examined by X-Ray Diffraction, Scanning Electron microscopy, Energy Dispersive X-Ray analysis, Cathodoluminescence, Atomic Force Microscopy and Nano-indentation. The composition and chemical bonding variation was found to be dependent on deposition conditions. All coatings were amorphous, fully dense and showed high hardness up to 33 GPa. It is suggested that the low friction coefficient of about 0.3, measured against Al2O3 using the pin-on-disc method, may be the result of the presence of C nanoclusters which are formed under the low energy deposition conditions. Films deposited on Stainless Steel had an onset of rapid thermal oxidation at 1150 °C in air as determined by thermogravimetric analysis. The films have a Tauc bandgap between 2.2 and 2.8 eV and were also exceptionally high electrical resistive which may indicate the presence of localised states.

Molecular dynamic simulation has been used to study how the sputtering characteristics of metal polycrystals are dependent on the mass m1 of bombarding ions of low-energy E0. The influence of target parameters on mass dependence of sputtering has been calculated for Al, Ba, Ce and Au, which were not previously studied. These metals have very different values of density ρ, the lattice constant d, and the surface binding energy Eb (the parameters that define the sputtering process). The features of sputtering characteristics for the metals studied are discussed.

A comparison of the performance of nonevaporable getter (NEG) films deposited using two different types of targets has been made to find the one that has the best pumping properties. For the first time, the NEG coating was deposited using a preformed Ti-Zr-V alloy target. The NEG film characterization and pumping properties have been studied in comparison with a film deposited using the commonly used three-wire twisted target. It was demonstrated that the alloy target produces a NEG coating with uniform composition both laterally and in depth. The composition of the film was found to be the same as the target. Film topography and microstructure with 5 nm grain sizes were found to be the same for both targets. The main result is that the activation temperature of the NEG coating deposited using the Ti-Zr-V alloy target is 160 °C, which is 20 °C lower than for NEG coatings deposited using three twisted wires.

The performance of a UHV vessel can be improved with a new CERN technology nonevaporable getter (NEG) coating, which is already widely used for accelerator vacuum chambers. Better understanding of the processes involved in NEG film deposition, activation, and poisoning should allow optimization and engineering of the film properties, which are necessary for a particular application. Ti–Zr–V NEG films were created by magnetron sputtering from a single Ti–Zr–V target, and the NEG performance and morphology dependence on deposition pressure, sputtering conditions, and substrate surface roughness have been investigated. It was found that the average grain size of the Ti–Zr–V film was 5–6 nm and was broadly independent of the substrate material and deposition conditions. However, film topography and density were shown to depend very much on the substrate surface roughness and deposition conditions. Rough substrates, high working pressures, and the absence of ion bombardment produced open columnar structures, w...

An experimental setup for studying the pumping and capacity properties of nonevaporable getter (NEG)-coated films has been designed and built in the ASTeC Vacuum Science Laboratory at Daresbury Laboratory. The measurement system is based on the dynamic expansion method with a gas injection system that is capable of injecting the residual gases present in a typical UHV system, such as H(2), CO, CO(2), and CH(4). The test particle Monte Carlo model was used for accurate evaluation of NEG film sticking probability from the pressure reading during gas injection. The experimental measurements with NEG-coated samples have shown that the NEG film can be poisoned during the NEG film activation (and/or regeneration) by molecules of CO and CO(2) desorbed from uncoated parts of the vacuum chamber. The effect of NEG film poisoning was reduced by lowering the temperature of the uncoated parts of the vacuum chamber during the NEG film activation and, as a result, a new activation procedure was developed for vacuum systems containing NEG-coated parts.

We report here on the synthesis, optical and structural analysis of amorphous and polycrystalline FeSi2 fabricated by co-sputter deposition. For comparisons, a range of deposition temperatures from room temperature up to 700 degrees C and post-anneals between 300 and 700 degrees C were performed. Optical absorption measurements were taken on all samples and results reveal that the bandgap remains direct in nature ranging from 0.897 to 0.949 eV. It was found that for amorphous thin films, annealing at low temperatures below 500 degrees C had little effect on the optical properties. The bandgap value and absorption coefficient only significantly increased upon annealing above 500 degrees C. This was found to be in good agreement with the transformation of the silicide from its amorphous phase to its crystalline beta-phase. In comparison, the deposition temperature was seen to affect the crystallinity of the as-deposited thin films and to vary both the optical and structural properties of the layers significantly. An increase in the deposition temperature not only decreased the bandgap energies but also significantly increased the photo-absorption by an order of magnitude.

The change of Auger-electron emission from polycrystals of disordered ferromagnetic NiPd 3 and Ni 3 Pd alloys, under ferro- to paramagnetic transition, has been studied experimentally. It has been shown that the intensity of the Auger-lines, which are formed because of transition of valent zone 3d 3/2 and 3d 5/2 electrons, has local maxima near the Curie point T C for the alloys. Thus, the sensitivity of Auger-electron emission to a magnetic state of the alloy has been established.

A dual ion beam system has been used to produce hard nanocomposite TiN/Si3N4 coatings on silicon substrate. Mechanical properties have been determined by nanoindentation and tribological properties have been measured by nanoscratch testing. Nanoindentation showed that harder nanocomposites exhibited higher ratios of hardness to modulus (H/E). The dependence of the resistance to plastic deformation (H3/E2) on hardness was approximately linear. The H/E value influenced the nanoscratch behaviour. Coatings with higher H/E showed higher critical loads for elastic–plastic transition and also the total coating failure occurring in front of the probe. However, coatings with higher H/E also exhibited an unloading failure, occurring behind the probe at much lower load than the loading failure. Optimizing this stress-related unloading failure could be more important for tribological applications.